Docs / Getting Started / Troubleshooting issues with FlyingPress

Troubleshooting issues with FlyingPress

Broken styles or layout or functionality

Disable CSS/JS optimizations

Most of the issues come from CSS or JavaScript optimizations. Disable both and see if that fixes the problems. If so, disable each optimization and see which one is causing the issue.

Common issues:

  • Critical CSS not compatible with heavy animations or JS dependent elements in the above-fold or use Force include selectors.
  • Deferring JavaScript causes issues with jQuery related scripts. Try enabling "Inline defer" or exclude "jquery" from defer.
  • Minify CSS/JS: Unfortunately, some scripts are incompatible with our minifier.

Disable all optimizations

If disabling CSS/JS optimizations doesn't fix the issue, try disabling all other optimizations and see if that fixes it. If so, enable them one by one and check.

Styling is broken with all optimizations disabled

If all the optimizations are disabled and the styles are still broken, there is probably some critical error in your HTML, usually unclosed tags. Check any custom code you've added and ensure all the tags are closed correctly.

Flash of unstyled content (FOUC)

Critical/Used CSS may not be up-to-date with the design. Try purging Critical/Used CSS.

Preloading cache not starting/stuck

Reason 1: There is an external caching layer (like Cloudflare APO, Varnish or Nginx cache).

Solution: Either disable the external caching layer or purge it first before purging the FlyingPress cache.

Reason 2: One of the optimizations is throwing an error which prevents caching.

Solution: Disable all optimizations and see preloading cache is working. If so, enable them one by one and figure out the one causing the issue. Checking PHP error logs can also help.

Reason 3: No valid sitemap.

Solution: FlyingPress uses a sitemap to get the list of pages to preload. Make sure you have a valid sitemap XML file which is publically accessible.

Images not lazy loading

FlyingPress uses the browser's native lazy loading. Native lazy loading performs best since it doesn't rely on JavaScript. The browser determines the threshold of lazy loading on several factors like connection speed, data saver mode, etc.

Performance score not improved

Make sure FlyingPress is serving cached pages. You can verify it as mentioned here: https://docs.flying-press.com/cache/cache-pages.

Depending on the site, every optimization may perform poorly on only some sites. So disable all optimizations, enable them one by one, and see which is causing the issue.

Not getting 100/100 score

There is no guarantee that FlyingPress will give a 100/100 score or pass Core Web Vitals. It depends on many factors like your hosting, plugins, theme, testing location, design, etc.

If you want to boost performance numbers, try adding "script" to JavaScript -> Load on user interaction. This will delay the execution of all JavaScript files.